1. Field of the Invention
The invention relates to a treatment device using dielectric barrier discharge lamps. The invention relates especially to improvement of a treatment device in which dielectric barrier discharge lamps are used in which excimer molecules are formed by a dielectric barrier discharge, and in which the light emitted by these excimer molecules is caused to react using the treatment gas.
2. Description of Related Art
Japanese patent disclosure document HEI 9-302326 describes a UV treatment device in which a lamp chamber and a treatment chamber are separated from one another by a window component.
FIG. 3 shows the arrangement of such a UV treatment device. In the figure, a UV treatment device 10 has a lamp chamber R and a treatment chamber T which are separated from one another by a UV transmission window component 11 made, for example, of silica glass. In the lamp chamber R, there are dielectric barrier discharge lamps 20a, 20b, 20c in the groove of a metal block 21 in which there are cooling water passages 22a, 22b through which cooling water flows. This lamp chamber R is filled with inert gas and is provided with an inlet 23a and an outlet 23b through which the inert gas flows. In the treatment chamber T, the article 1 to be treated is placed on a holding frame 31 which receives the UV radiation emitted by the dielectric barrier discharge lamps 20. The treatment chamber T is also provided with an inlet 32 which is used to deliver treatment gas into the interior. The arrangement and the description of other details are described in addition in the detailed description of the invention.
Dielectric barrier discharge lamps 20 are disclosed, for example, in Japanese patent disclosure document HEI 2-7353 (U.S. Pat. No. 4,983,881). It describes a radiator, i.e., a dielectric barrier discharge lamp in which a discharge vessel is filled with a discharge gas which forms excimer molecules, in which furthermore excimer molecules are formed by a dielectric barrier discharge, which is also called an ozone production discharge or a silent discharge, as is described in the revised edition of the Discharge Handbook, Electro Society, June 1989, 7th edition, page 263, and in which light is emitted by the excimer molecules.
Furthermore, published German Patent Application DE 4022279 A1 discloses a dielectric barrier discharge lamp which is operated with a few MHz and in which the discharge vessel has a cylindrical shape, at least part of the discharge vessel acting as a dielectric which carries out the dielectric barrier discharge. At least part of this dielectric transmits vacuum UV light (light with wavelengths of less than or equal to 200 nm) which is emitted by the excimer molecules. In the dielectric barrier discharge lamp described herein, the outside of the discharge vessel is provided with a mesh electrode as one of the electrodes.
These dielectric barrier discharge lamps have various advantages which conventional low-pressure mercury discharge lamps and conventional high pressure arc discharge lamps do not have. One of the advantages is that vacuum UV light is intensively emitted with a single wavelength.
In the UV treatment device shown in FIG. 3, dry surface cleaning, surface oxidation, surface activation, photo-CVD treatment and the like of the article 1 to be treated can be carried out by the vacuum UV light emitted by the dielectric barrier discharge lamps, for example, by light with a wavelength of 172 nm.
The light emitted by the dielectric barrier discharge lamps here has a wavelength of at most 200 nm, specifically a wavelength of 172 nm, 146 nm, or 126 nm. There is the disadvantage that, upon passage through the UV transmission component, absorption by this component takes place and therefore the amount of light is reduced. This reduction of the amount of light means a reduction in the amount of light which reaches the article 1 to be treated; this results in the major disadvantage that the above described treatment cannot be advantageously carried out.
In a low-pressure mercury lamp which emits light with a wavelength of 254 nm, this reduction in the amount of light by the UV transmission component does not occur to a degree which is a problem in practice. It can be stated that it is a new task which clearly arises in a dielectric barrier discharge lamp which emits UV light with a wavelength of less than or equal to 200 nm, more specifically less than or equal to 172 nm.
On the other hand, in this device, the UV transmission component is indispensable. The reason for this is the following:
1. The dielectric barrier discharge lamp has a special arrangement in which there is an electrode on the outside of the discharge vessel. The UV transmission component is used to prevent the extremely small parts of the electrode from vaporizing and precipitating on the article to be treated.
2. Since the vacuum UV light which is emitted by the dielectric barrier discharge lamps is absorbed by oxygen with an extremely high probability, it is advantageous to form a lamp chamber space in which there is no oxygen. In the case in which the discharge vessel has a circular cross sectional shape, the linear distance to the article to be treated on the outside peripheral surface of the discharge vessel is different. An arrangement of the UV transmission component, especially a flat transmission component, is therefore a very good idea, in the sense of preventing the scattering of the amount of light of the UV radiation which reaches the article to be treated. One such technology is disclosed, for example, in Japanese patent disclosure document HEI 8-124540.
The object of the present invention is to advantageously eliminate the disadvantage of attenuation of the radiant light from the dielectric barrier discharge lamps by the UV transmission component in a treatment device or a treatment process in which dielectric barrier discharge lamps are used as the light source and in which the lamp chamber and the treatment chamber are separated from one another by a UV transmission component.
The object is achieved in accordance with the invention in a treatment device using dielectric barrier discharge lamps and with:
a lamp chamber in which dielectric barrier discharge lamps are located and there is an inert gas atmosphere;
a treatment chamber in which an article to be treated is located and there is a treatment gas atmosphere, and
a UV transmission component by which the lamp chamber and the treatment chamber are separated from one another, in that, in the lamp chamber and the treatment chamber, there are a means for determining the gas pressure within the respective chamber, a means for delivering gas to the inside and a means for discharging gas, and a means which regulates the pressure of the gas atmosphere within the lamp chamber and the pressure of the gas atmosphere of the treatment chamber relative to one another by determining the gas pressures of the lamp chamber and the treatment chamber.
The object is achieved, in one development of the invention, in a treatment device using dielectric barrier discharge lamps, in that in addition to the above described arrangement, the pressure of the gas atmosphere of the lamp chamber is regulated according to the pressure of the gas atmosphere of the treatment chamber.
The object is moreover achieved in a treatment device using dielectric barrier discharge lamps in that, in addition to the above described arrangement, the gas atmosphere of the lamp chamber is regulated with respect to the pressure of the gas atmosphere of the treatment chamber such that the difference between the two is within xc2x10.2 atm.
The object is furthermore achieved in a treatment device using dielectric barrier discharge lamps in that, in addition to the above described arrangement, the gas atmosphere of the lamp chamber is regulated such that it is essentially identical to the pressure of the gas atmosphere of the treatment chamber.
The object is furthermore achieved in accordance with the invention in a treatment process using dielectric barrier discharge lamps by the following process steps:
Inert gas is delivered into the lamp chamber in which there are dielectric barrier discharge lamps;
Before or after this delivery of the inert gas or simultaneously with it, a treatment gas is admitted into the treatment chamber in which there is an article to be treated and which is separated from the lamp chamber by a UV transmission component;
The gas pressure of the treatment chamber and the gas pressure of the lamp chamber are each determined; and
Based on the determination values thereof, the two gas pressures are regulated relative to one another.
According to one version of the invention, in the treatment process using dielectric barrier discharge lamps, the object is achieved in that, in addition to the above described arrangement, the above described relative regulation is carried out such that the difference between the two gas pressures is within xc2x10.2 atm.
The object is furthermore achieved in a treatment process using dielectric barrier discharge lamps in that in addition to the above described arrangement the above described relative regulation is carried out such that the two gas pressures are made essentially the same size.
The invention is further described below using the drawings.
FIG. 1 shows a schematic of a treatment device as claimed in the invention using dielectric barrier discharge lamps;
FIGS. 2(a) and (b) each show a schematic of a dielectric barrier discharge lamp in a treatment device as claimed in the invention and
FIG. 3 shows a schematic of a conventional treatment device using dielectric barrier discharge lamps.